Antiinflammatory and analgesic transdermal gel containing Ketoprofen

Abstract: Transdermal gels comprising (1) a nonsteroidal antiinflammatory drug of propionic acid derivatives as an effective components (2) poloxamer (3) one or more agent selected from a lower alcohol, propylene glycol, polyethylene glycol and glycerin (4) one or more agent selected from fatty acids, fatty alcohols and methol (5) water or a buffer solution. The gels form thin and pliable films, which are easily washable with water. They possess prolonged antiinflammatory and analgesic activities and excellent physicochemical stability with less systemic side effects and gastric irritation.

Description: The present invention relates to an antiinflammatory and analgesic transdermal gel containing ketoprofen, as an effective ingredient. In particular, the present invention relates to a novel antiinflammatory and analgesic transdermal gel which is water-soluble and provides comparable anti inflammatory and analgesic activities to the oral administration while significantly reducing the systemic side effects and the gastrointestinal irritation after the oral administration of the drug. Typical examples of nonsteroidal antiinflammatory drug of propionic acid derivatives include ketoprofen, ibuprofen, flurbiprofen, naproxen, fenoprofen, benoxaprofen, indoprofen, pirprofen, carprofen, oxaprozin, pranoprofen, suprofen, alminoprofen, butibufen and fenbufen . They have potent antiinflammatory and analgesic activities and widely used for the treatment of rheumatic arthritis and its related conditions. Conventionally, these drugs have been administered orally in the form of solid preparations such as tablets and capsules. However, they have accompanied systemic side effects or gastrointestinal irritation following their oral administration. In order to reduce these side effects, these drugs have been formulated as transdermal preparations based on the fact that the skin permeability of these nonsteroidal antiinflammatory drugs are known to be relatively higher than other nonsteroidal antiinflammatory drugs. For examples, JP 58-39616, JP 58-83622, JP 58-103311, JP 61-238723 and USP 4,393,076 and 4,534,980 disclosed to formulate nonsteroidal antiinflammatory drugs of propionic acid derivatives into transdermal preparations, generally an ointment or a cream. They claimed that the systemic side effects and gastrointestinal irritation of these drugs were significantly reduced while satisfied therapeutic effects were obtained. In these patents, they usually used carboxyvinyl polymer or hydroxypropylmethylcellulose as a gel base in the formulation of transdermal preparations of the drugs. However, the skin permeations of the drugs from their preparations were not enough to achieve pharmacological effects comparable to the oral administration of the drugs due to the low percutaneous absorption of the drugs from the preparations and, thus, a large amount of the preparation should be applied to achieve a desired efficacy. As a result of extensive investigations with attempts to improve the shortcomings of the existing patents and products, the present inventors have succeeded in establishing a novel transdermal gel containing ketoprofen. The gel is water-soluble, has high skin permeation rate and, thus, excellent antiinflammatory and analgesic activities comparable to its oral administration. It, also, showed lowered systemic side effects and gastrointestinal irritation and good physicochemical stability. The present invention provides an antiinflammatory and analgesic transdermal gel which consists essentially of (a) 0.5-5% by weight of ketoprofen; (b) 10-30% by weight of a poloxamer® as a gel forming agent; (c) 0-30% by weight of one or more agents selected from ethyl alcohol, isopropyl alcohol, propylene glycol, polyethylene glycol and glycerine; (d) one or more agents selected from lauric acid, oleic acid, capric acid, myristic acid, lauryl alcohol, oleyl alcohol and menthol in an amount sufficient that these compounds act as penetration enhancers, however, not exceeding 10% by weight; optionally preservatives and flavors, and total to 100% with water or a buffer solution, wherein the gel pH is controlled to the value around the pKa of ketoprofen. The transdermal gels of the present invention can be prepared by dissolving a mixture comprising ketoprofen; poloxamer®; and one or more agent selected from ethyl alcohol, isopropylalcohol, glycerin, propylene glycol and polyethylene glycol; one or more agent enhancers selected from fatty acids, fatty alcohols and menthol; and, if necessary, one or more other agent including a preservative, a flavor, in water or a buffer solution. More specifically, the lower alcohols used in the present invention are ethanol and isopropyl alcohol, and poloxamer derivatives may be poloxamer® 407 and poloxamer® 338, poloxamer® 237 and others. The concentrated aqueous solution of poloxamer, used as a gel forming agent of this invention, is a low viscous transparent liquid at refrigerator temperature or lower, but turns to a clear semisolid gel on heating to room or body temperature. The polymer also possesses several properties which make it particularly suitable for use in the formulation of transdermal dosage forms. These include low toxicity and skin irritation, excellent compatibility with other chemicals, high solubilizing capacity for different drugs and good drug release characteristics. Polyethylene glycol may be polyethylene glycol 200, polyethylene glycol 300, polyethylene glycol 400, polyethylene glycol 600, polyethylene glycol 1000 and others. Fatty acids are lauric acid, oleic acid, capric acid, myristic acid and others, and fatty alcohols are lauryl alcohol, oleyl alcohol and others. In the present invention, the pH of the gel is controlled to the value around the pKa of ketoprofen. The preservative may be benzoic acid, sodium benzoate, methyl ρ-hydroxybenzoate, ethyl ρ-hydroxybenzoate, propyl ρ-hydroxybenzoate, butyl ρ-hydroxybenzoate or a mixture thereof. The gel compositions of this invention comprise desirably 0.5-5% of ketoprofen; 10-30% of poloxamer; and 0-30% of lower alcohol or polyethylene glycol or propylene glycol or glycerin; fatty acid or fatty alcohol or menthol in an amount sufficient that these compounds act as penetration enhancers, however not exceeding 10%. When the gel of the present invention is applied on skin, it forms a thin and pliable film from which the drug is released slowly and continuously, resulting in prolonged antiinflammatory and analgesic activities which last for one day. Propylene glycol, polyethylene glycol and glycerin act as a moisturizer as well as cosolvent. Fatty acid or fatty alcohol or menthol act as a penetration enhancer. The present transdermal gels can be prepared simply as follows: the drug and poloxamer® are heated at a temperature higher than 90°C to obtain a homogeneous liquid mixture, and then the mixture is cooled to 40 - 60°C. Separately, water or a buffer solution in which the other additives have been dissolved is prepared and added into the above liquified mixture. When it is cooled to room temperature or in the refrigerator, the gel forms. The produced transdermal gels of ketoprofen are water-soluble, transparent with good texture, and exhibit excellent antiinflammatory and analgesic activity with less gastrointestinal irritation, as shown in the following Experiments. Hereafter, the present invention will be described in more detail with reference to the following examples, but is not deemed to be limited only thereto. Throughout the examples, all percents are by weight. Example 1 Ketoprofen 3% Poloxamer® 407 15% Polyethylene glycol 300 3% Ethanol 18.5% Menthol 0.3% Methyl ρ-hydroxybenzoate 0.17% Propyl ρ-hydroxybenzoate 0.02% pH 4.5 buffer solution 60.01% Three grams of ketoprofen and 15g of poloxamer® 407 were heated at 105°C for 10 minutes to obtain a liquified mixture and then cooled to 60°C. Separately, 0. 17g of methyl ρ-hydroxybenzoate, 0. 02g of propyl ρ-hydroxybenzoate and 0.3g of menthol were dissolved in 18.5g of ethanol, and 3g of polyethylene glycol 300 was mixed with 60. 01g of pH 4.5 buffer solution. After the alcohol solution was mixed with the above mixture at 60°C, the aqueous solution was added into the final mixture at 60°C to obtain a ketoprofen gel. Example 2 Ketoprofen 3% Poloxamer® 407 17% Polyethylene glycol 4000 5% Ethanol 20% Lauric acid 5% Water 50% Three grams of ketoprofen and 17g of poloxamer® 407 were heated at 105°C for 10 minutes to obtain a liquified mixture and then cooled to 60°C. Separately, 5g of lauric acid was dissolved in the mixture of 5g of polyethyleneglycol 4000 and 20g of ethanol, which was mixed into the above liquified mixture at 60°C. Finally, 50g of water was added under vigorous stirring to obtain a ketoprofen gel. Experiment 1 Antiinflammatory activity on carrageenan-induced paw edema in rats: Male Sprague-Dawley rats weighing about 200g were used as the test animals. Three hours before carrageenan injection, the gel in the Example 1 was applied on the left hind paw of the rats at the dose of 50mg. Then, 0.1 ml of 1% carrageenan in physiological saline was injected into the paw subplantarly. Immediately and three hours after the carrageenan injection, the volume of the pain was measured using a plethysmometer(Ugo Basile Co. Italy), and the percent swelling of the paw and the percent inhibition of the edema formation were calculated as follows: % swelling = paw volume at 3 hrs after carrageenan injection - initial paw volume initial paw volume x 100 % inhibition = 1 - % swelling of drug-treated group % swelling of control group x 100 The results are presented in Table 1. Group No. of Rat % Swelling % Inhibition Control 8 77.2 ± 19.8 - Example 1 (ketoprofen gel) 6 25.6 ± 6.2 66.8 As can be seen in Table 1, the above transdermal gel according to the present invention exhibited significant decrease of % swelling of the paw compared to the control. The % inhibition of the edema formation by the gels was in the range of 58 to 66%, which is the maximum inhibition, 60%, obtainable with this model. Experiment 2 Antiinflammatory activity on adjuvant-induced arthritis inhibition in rats: Male Sprague-Dawley rats weighing about 250g were anesthetized slightly and an emulsion (6mg/ml) of Mycobacterium butyricum in mineral oil was inoculated subplantarly into the left hind paw of rats. The gel in the Example 1 was applied on the innoculated paw at the dose of 50mg once daily from 12th day to 20th day after the injection. On the 21th day after the injection, the volume of the paw was measured according to the method in the Experiment 1 to determine the edema formation of the paw injected with the adjuvant. The results are presented in Table 2 below. Group No. of Rats % Swelling Control 10 2.30 ± 0.37 Example 1 (ketoprofen gel) 10 0.79 ± 0. 28 As shown in Table 2, the transdermal gels according to the present invention have excellent antiinflammatory activity since they decreased paw edema induced by the subplantar injection of adjuvant, by more than 50% compared with the control group. Experiment 3 Percutaneous absorption: Four male Sprague-Dawley rats weighing 200g ± 20g were used to evaluate the percutaneous absorption of ketoprofen from the gel of Example 1. Prior to application of the gel, hair at the rat ventral skin area was carefully removed with an electrical clipper. Fifty mg of the gel was uniformly applied over the area of approximately 2 cm X 3 cm with gentle rubbing. At predetermined time intervals, 250 ul of blood was collected into a microcentrifuge tube containing heparin to obtain a plasma sample. The concentration of ketoprofen in rat plasma was quantitated with High Performance Liquid Chromatography. The results are presented in Table 3 below. Time Elapsed (hr) Concentration of Ketoprofen in Plasma Time Elapsed (hr) Concentration of Ketoprofen in Plasma 1 225.9 ± 63.1 10 404.5 ± 89.1 2 452.8 ± 68.1 12 341.5 ± 59.0 3 739.1 ± 216.9 16 263.3 ± 21.6 4 798.8 ± 178.8 24 183.9 ± 33.3 6 810.0 ± 174.9 36 76.6 ± 11.4 8 588.7 ± 120.1 48 63.5 ± 6.1 The maximum concentration of ketoprofen after its oral administration to rats are known to appear at 0.25-0.5 hrs postdose. After the transdermal application of the gel of Example 1, however, the absorption of ketoprofen was so slowered that the maximum concentration of the drug was 6 hrs postdose as can be seen in Table 3. And, also, the ketoprofen concentration in plasma was maintained plateau relatively over several hours after the transdermal application, even though much lower than that after the oral administration of the drug. Experiment 4 Gastric ulcer formation: Male Sprague-Dawley rats weighing around 200g were used as the test animals. Food was withheld from the rats for 24 hrs prior to dosing while water was allowed freely throughout the experiment. The gel in the Example 1 was applied gently, at the dose of 50mg/kg, on the dorsal skin of 2cm x 3cm where the hair was removed. As a reference, the rats of the control group were administrated ketoprofen orally as a suspension in physiological saline at the dose of 10mg/kg. Six hours after the administration, the rats were sacrificed and ulcer formation in the stomach was scored as follows: 0; normal, 1; reddened mucosa, 2; one to four small ulcer (smaller than 2mm in diameter), 3; more than four small ulcer or one large ulcer (larger than 2mm in diameter), 4; more than one large ulcer. The score of two or higher was regarded as ulcer formation. The results are presented in Table 4 below. Administration Route Drug or Preparation Dose No. of Rat Ulcer Is Produced Average Ulcer Score Oral Control (ketoprofen) 10mg/kg 6/6 2.91 Transdermal Example 1 (ketoprofen gel) 50mg/kg 2/6 1.88 As can be seen in Table 3, when ketoprofen was formulated into gels according to the present invention and administrated transdermally, gastric ulcer formation was much lower even with 5-fold doses than the oral administration. The ulcer formation were also observed after the percutaneous administration of the gels, indicating that a significant amount of the drug permeated the skin and was absorbed into the blood circulation. Experiment 5 Stability test: The gel in Example 1 was stored at 4°C, 25°C and 40°C. After 6 months, the samples were examined whether the initial texture of each gel was maintained or not. The change of color was tested visually against white background and samll quantities of the gels were subjected to microscopic examination to identify any recrystallization of the drug. The amount of the drug in the gel was quantitated using High Performance Liquid Chromatography and the results are presented in Table 5 below. Storage Temperature Amount Remaining(%) Appearance Recrystallization Example 1 (ketoprofen gel) 4°C 103.2 no change not observed 25°C 98.2 no change not observed 40°C 99.2 no change not observed As shown in Table 4, any change of appearance or recrystallization in the gel was observed and little change of the amount of drug in the gel was detected compared to the initial amount, indicating excellent physicochemical stability of the gel.

Claims: An antiinflammatory and analgesic transdermal gel which consists essentially of (a) 0.5-5% by weight of ketoprofen; (b) 10-30% by weight of poloxamer as a gel forming agent; (c) 0-30% by weight of one or more agents selected from ethyl alcohol, isopropyl alcohol, propylene glycol, polyethylene glycol and glycerine; (d) one or more agents selected from lauric acid, oleic acid, capric acid, myristic acid, lauryl alcohol, oleyl alcohol and menthol in an amount sufficient that these compounds act as penetration enhancers, however, not exceeding 10% by weight; optionally preservatives and flavors, and total to 100% with water or a buffer solution, wherein the gel pH is controlled to the value around the pKa of ketoprofen.

Inventors: CHI SANG-CHEOL, CHUN HEUNG-WON, TAN HYUN-KWANG, CHI, SANG-CHEOL, CHUN, HEUNG-WON, TAN, HYUN-KWANG
Applicants: IL DONG PHARMA, IL-DONG PHARM. CO., LTD.
Application year: 1994
Main classification: A61K47
IPC codes: A61K47, A61K31, A61K9